不同淬火介质对17CrNiMo6重载齿轮渗碳钢组织与性能的影响

Effects of quenching media on microstructure and mechanical properties of 17CrNiMo6 steel for carburized heavy duty gear

研究了17CrNiMo6重载齿轮渗碳钢分别在快速淬火油(K油)和硝盐两种介质中淬火+低温回火处理后的组织和性能。利用光学显微镜(OM)观察了17CrNiMo6钢在两种介质中淬火后的微观组织,用显微硬度计和表面硬度计测试了硬度分布,用万能试验机进行了力学性能测试。结果表明,试样在K油中淬火硬度分布曲线在2 mm处出现陡降,而在硝盐中淬火后的硬度分布比较平缓;K油淬火及硝盐淬火后得到的表层组织中碳化物都为细小粒状,心部组织都为板条马氏体和少量的游离铁素体,而用K油淬火的马氏体针比硝盐淬火得到的马氏体针更细小;在K油和硝盐中淬火后的力学性能(ReL、Rm、A、Z)均满足标准要求,且K油中淬火试样的力学性能优于在硝盐中淬火后的力学性能。

Microstructure and mechanical properties of 17CrNiMo6 steel for carburized heavy duty gear quenched in rapid quenching oil （K oil） and nitrate molten salt, respectively, then tempered at low temperature have been investigated. Microstructure of 17CrNiMo6 steel for earbmized heavy duty gear quenched was observed and investigated by means of optical microscope （ OM ） , then the hardness distribution was measured by the microhardness and surface rockwell testers, meanwhile, the mechanical properties tests were conducted by electronic universal testing machine. The results show that the hardness profile of the hardened layer quenched in K oil steeply drops in 2 mm from surface, while that quenched in nitrate molten salt is relatively smooth. After quenched in K oil or nitrate molten salt, the carbide morphology near surfaee is similar, both are fine granular carbides, and the core mierostrueture consists of a small amount of lath martensite and free ferrite, however the martensite needles obtained by quenched in K oil are smaller than that in nitrate mohen salt. Mechanical properties （ReL, Rm、 A, Z） of the specimens quenched in different quenching media can meet standard requirements, furthermore the mechanical properties quenched in K oil are better than that in nitrate molten salt.